Great sounding Phaser Pedal, The Original, not the later china copy, the Key and Bass Version with the Programm Mod. But as well great for guitar!!!

The TC Electronic TC XII B/K is a vintage 1980s phaser pedal designed for bass and keyboards, a variant of the original TC XII for guitar. It features controls for Speed, Depth, and a unique Function knob that sets the phaser character from peak to linear to notch. A three-position Filter switch allows you to choose between 4, 8, or 12 phaser poles. The B/K version has internal modifications to lower the effective frequency range for bass and keyboard use